Vinegar is by far the cheapest. Tea tree oil is expensive, but it is a broad spectrum fungicide and seems to kill all the mold families it contacts. The problem is that it has a very strong smell, but that dissipates in a few days. Grapefruit seed extract is also expensive, but has no smell.

Mold can be dangerous to your health, even if you aren't allergic. Many people react to mold by getting tired and even depressed. Try to stay on top of moisture and mold as soon as either arises. Dry out anything that is damp, such as basements (use a dehumidifier) and carpets. Fix leaks in plumbing and roofs. Wipe up spills. Make sure water doesn't escape from shower curtains. Vigilance will pay off!

Tea Tree Treasure

Nothing natural works for mold and mildew as well as this spray. I've used it successfully on a moldy ceiling from a leaking roof, on a musty bureau, a musty rug and a moldy shower curtain. Tea tree oil is expensive, but a little goes a very long way. Note that the smell of tea tree oil is very strong, but it will dissipate in a few days.

2 teaspoons tea tree oil

2 cups water

Combine in a spray bottle, shake to blend, and spray on problem areas. Do not rinse. Makes about 2 cups, lasts indefinitely.

Grapefruit Seed Extract

Combine in a spray bottle, shake to blend, and spray on problem areas. Do not rinse. Makes about 2 cups, lasts indefinitely.

Vinegar Spray

Straight vinegar reportedly kills 82 percent of mold. Pour some white distilled vinegar straight into a spray bottle, spray on the moldy area, and let set without rinsing if you can put up with the smell. It will dissipate in a few hours. If you don't like the smell of vinegar, you can add essential oils for a more mellow scent.